DISCREPANCY BETWEEN RADIOIMMUNOASSAY AND RADIOLIGAND-RECEPTOR ASSAY OF LUTEINIZING HORMONE RELEASED IN VITRO BY PITUITARY TISSUE FROM MALE RATS OF DIFFERENT AGES

1975 ◽  
Vol 65 (2) ◽  
pp. 265-273 ◽  
Author(s):  
R. M. SHARPE ◽  
M. SHAHMANESH ◽  
M. G. ELLWOOD ◽  
M. HARTOG ◽  
P. S. BROWN
Keyword(s):  
Luteinizing Hormone ◽  
Close Agreement ◽  
Male Rats ◽  
Male Rat ◽  
Receptor Assay ◽  
Pituitary Glands ◽  
Lh Release ◽  
Radioligand Receptor Assay ◽  
Lh Rh

SUMMARY Anterior pituitary glands from male rats aged 21, 40, 60 or 95 days were incubated in medium containing 0, 2 or 20 ng luteinizing hormone-releasing hormone (LH-RH)/ml. Incubates were assayed for LH by radioimmunoassay (RIA), by the radioligand-receptor assay (RLA) using testicular homogenates as the source of receptor and, in some instances, by the ovarian ascorbic acid depletion assay (OAAD). Irrespective of the dose of added LH-RH, glands from rats aged 40 and 60 days always showed a higher release of LH, as determined by RLA, than glands from animals aged 21 or 95 days. Measurement by RIA showed a similar pattern to RLA in the basal release of LH, but in the presence of LH-RH showed little difference in LH release by glands from rats aged 40, 60 or 95 days. The LH release caused by the higher concentration of LH-RH was always greater when measured by RLA than by RIA. Assay of comparable incubates by OAAD showed close agreement with RLA estimates in four incubations (mean index of discrimination 1·07; range 0·86–1·18) and consistent disagreement with RIA estimates (1·64; range 1·38–1·99). In contrast to the results with incubates, homogenates of pituitary glands from male rats of various ages showed close agreement of estimates by RLA, RIA and OAAD. These results suggest that RIA underestimates the LH-RH-stimulated release of LH in vitro from the male rat pituitary during some stages of sexual maturation.

IMMATURE RAT PITUITARY GLANDS IN VITRO: AGE- AND SEX-RELATED CHANGES IN LUTEINIZING HORMONE RELEASING HORMONE-STIMULATED GONADOTROPHIN RELEASE

1977 ◽  
Vol 73 (2) ◽  
pp. 309-319 ◽  
Author(s):  
J. DULLAART
Keyword(s):  
Male Rats ◽  
Steady Increase ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Lh Release ◽  
The One ◽  
Lh Rh ◽  
Lh Releasing Hormone

SUMMARY Pituitary glands from immature female and male rats aged between 5 and 30 days were incubated in vitro and the effect of LH releasing hormone (RH) on the release of LH and FSH was studied. Pituitary gonadotrophin contents were also measured. Gonadotrophin release showed changes with age as well as sex differences: after LH-RH stimulation the female pattern of release of LH and FSH (expressed per mg pituitary tissue) showed a peak at day 15; the male pattern of LH release was characterized by a steady increase with age, whereas FSH release stayed more or less constant from day 10 onwards. In both sexes the LH:FSH ratio increased with age, both in pituitary gonadotrophin content and in the mixture of gonadotrophins released. It is discussed, that the prepubertal development of pituitary gonadotrophic function might be determined on the one hand by rather autonomous growth processes (more or less similar in female and male hypophyses) and on the other hand by modulating influences of sex steroid hormones, which are different in female and male animals.

Stimulatory effect of thyrotrophin-releasing hormone (TRH) on the release of luteinizing hormone (LH) from rat anterior pituitary cells in vitro

1983 ◽  
Vol 61 (2) ◽  
pp. 186-189 ◽  
Author(s):  
Noboru Fujihara ◽  
Masataka Shiino
Keyword(s):  
Luteinizing Hormone ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Anterior Pituitary Cells ◽  
Lh Release ◽  
Lh Rh

The effect of thyrotrophin-releasing hormone (TRH, 10−7 M) on luteinizing hormone (LH) release from rat anterior pituitary cells was examined using organ and primary cell culture. The addition of TRH to the culture medium resulted in a slightly enhanced release of LH from the cultured pituitary tissues. However, the amount of LH release stimulated by TRH was not greater than that produced by luteinizing hormone – releasing hormone (LH–RH, 10−7 M). Actinomycin D (2 × 10−5 M) and cycloheximide (10−4 M) had an inhibitory effect on the action of TRH on LH release. The inability of TRH to elicit gonadotrophin release from the anterior pituitary glands in vivo may partly be due to physiological inhibition of its action by other hypothalamic factor(s).

Wen-Jing-Tang, a Traditional Chinese Herbal Medicine Increases Luteinizing Hormone Release In Vitro

1986 ◽  
Vol 14 (03n04) ◽  
pp. 157-160 ◽  
Author(s):  
Akira Miyake ◽  
Jin-Woo Lee ◽  
Keiichi Tasaka ◽  
Shirou Ohtsuka ◽  
Toshihiro Aono
Keyword(s):  
Herbal Medicine ◽  
Luteinizing Hormone ◽  
Chinese Herbal Medicine ◽  
Female Rats ◽  
Normal Female ◽  
Traditional Chinese Herbal Medicine ◽  
Chinese Herbal ◽  
Lh Release ◽  
Lh Rh

For examination of the effect on luteinizing hormone (LH) release of Wen-Jing-Tang, a traditional Chinese herbal medicine, the pituitary from normal female rats in diestrus was perifused alone or in sequence with the mediobasal hypothalamus (MBH) in a sequential double-chamber perifusion system. Wen-Jing-Tang at 5 or 500 μg/ml induced significant LH release (60-95 % increase) from the pituitary in series with the MBH, but had no effect on LH release from the pituitary perifused alone. These data suggest that Wen-Jing-Tang induces LH release from the pituitary through hypothalamic LH-RH.

LH-RH-dependent synthesis of protein necessary for LH release from rat pituitary glands in vitro

1976 ◽  
Vol 5 (1-2) ◽  
pp. 151-160 ◽  
Author(s):  
J. De Koning ◽  
J.A.M.J. Van Dieten ◽  
G.P. Van Rees
Keyword(s):  
Rat Pituitary ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh

POSSIBLE INTERACTION OF LUTEINIZING HORMONE-RELEASING FACTOR WITH OTHER HYPOTHALAMIC RELEASING FACTORS AT THE LEVEL OF THE ADENOHYPOPHYSIS

1969 ◽  
Vol 44 (3) ◽  
pp. 405-410 ◽  
Author(s):  
D. B. CRIGHTON ◽  
H. P. G. SCHNEIDER ◽  
S. M. McCANN
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Gel Filtration ◽  
The Other ◽  
Male Rats ◽  
Corticotrophin Releasing Factor ◽  
Lh Release ◽  
Releasing Factors ◽  
Factor C

SUMMARY Anterior pituitary halves from adult male rats were incubated in vitro for 6 hr. in tissue culture Medium 199. Luteinizing hormone (LH) released from these glands under the influence of purified preparations of growth hormone-releasing factor (GH-RF), growth hormone-inhibiting factor (GH-IF), corticotrophin-releasing factor (C-RF) and follicle-stimulating hormone-releasing factor (FSH-RF) was determined by the ovarian ascorbic acid depletion (OAAD) assay. The effects of these factors, both alone and together with purified luteinizing hormone-releasing factor (LH-RF), were examined and compared with the response to purified LH-RF alone. While LH-RF consistently produced significant increases in LH release, none of the other factors did so, although FSH-RF showed some indication of LH-releasing activity, probably due to incomplete separation from LH-RF on the Sephadex gel filtration column used for purification. The LH released in response to LH-RF was not affected by the presence of any of the other factors. An apparent slight augmenting effect of FSH-RF could be accounted for by its contamination with LH-RF. The results are discussed in relation to the physiological mechanisms concerned in modifying LH release from the adenohypophysis.

BIOASSAY OF INHIBIN-LIKE ACTIVITY USING PITUITARY CELLS IN VITRO

1979 ◽  
Vol 80 (1) ◽  
pp. 91-102 ◽  
Author(s):  
F. H. DE JONG ◽  
S. D. SMITH ◽  
H. J. VAN DER MOLEN
Keyword(s):  
Cell Culture ◽  
Luteinizing Hormone ◽  
Male Rats ◽  
Pituitary Cells ◽  
Lh Rh ◽  
Dose Dependent ◽  
Higher Doses ◽  
Ovarian Follicular Fluid ◽  
Sensitive Method

The secretion of follicle-stimulating hormone (FSH) by the pituitary gland appears to be partially regulated by a protein hormone, inhibin, which is produced in the Sertoli cells of the testis and is also present in ovarian follicular fluid (FF). The aim of the present study was to develop a sensitive method for the detection and estimation of inhibin-like activity, using dispersed pituitary cells in culture. Pituitary cells from adult male rats were dispersed and precultured for 3 days. After renewal of the medium (2 ml), samples to be tested for inhibin-like activity were added and culture was continued for a further 3 days. A dose-dependent suppression of the concentration of FSH in the medium (λ = 0·17–0·22) was observed after addition of FF (0·05–1 μl) or Sertoli cell culture medium (SCCM, 0·05–1 ml). Luteinizing hormone (LH) concentrations were not affected with these doses of FF, but SCCM and higher doses of FF caused a significant increase in the concentration of LH in the medium. During an additional 6 h of culture in the presence of luteinizing hormone releasing hormone (LH-RH), FF and SCCM suppressed the release of both FSH (λ = 0·07–0·11) and LH in a dose-dependent way. Cellular content of FSH, but not of LH, was decreased after these treatments. These results could not be explained by damage to the pituitary cells, by degradation of FSH or LH-RH, or by effects of steroids. It is concluded that this pituitary cell culture system can be used as a sensitive method for the estimation of inhibin-like activity in FF and SCCM.

STIMULATION OF PROSTAGLANDIN ACCUMULATION IN THE RAT ANTERIOR PITUITARY GLAND BY LUTEINIZING HORMONE RELEASING HORMONE IN VITRO

1977 ◽  
Vol 75 (2) ◽  
pp. 277-283 ◽  
Author(s):  
N. BARDEN ◽  
A. BETTERIDGE
Keyword(s):  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Lh Release ◽  
Lh Rh ◽  
Stimulation Of

The addition of luteinizing hormone releasing hormone (LH-RH) to cultures of monolayers of rat anterior pituitary cells was shown to increase both the concentrations of prostaglandins E1 and E2 (PGE) in the cells and the release of LH over similar ranges of concentrations of LH-RH (10−6 to 10−10 mol/l). The peak concentration of PGE was observed after 2·5 h. The stimulation of the level of PGE in the cells by LH-RH was completely inhibited by two inhibitors of prostaglandin synthetase, which only partially inhibited the stimulation of LH release. Therefore the increased concentration of PGE was not obligatory for the effect of LH-RH on LH release. It was also shown that monobutyryl cyclic AMP stimulated the intracellular concentration of PGE and it is suggested that the stimulation of PGE levels may be mediated by increased levels of cyclic AMP in the cells after the addition of LH-RH.

Effect of Ca2+ deprivation on release of luteinizing hormone induced by luteinizing hormone releasing hormone from female rat pituitary glands in vitro

1982 ◽  
Vol 94 (1) ◽  
pp. 11-20 ◽  
Author(s):  
J. de Koning ◽  
A. M. I. Tijssen ◽  
J. A. M. J. van Dieten ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Initial Phase ◽  
Phase Response ◽  
Ovariectomized Rats ◽  
Second Phase ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh ◽  
Intact Rats

Continuous exposure of hemi-pituitary glands from intact female rats to LH releasing hormone (LH-RH) in vitro displayed three phases in the pattern of LH release: during the first hour release of LH was low (first phase response), then it increased to a higher level during the second hour and remained constant during the next 2 h (second phase response), after which there was a refractoriness of LH release (third phase response). The initial phase response of pituitary glands from intact rats was blocked by EGTA (a Ca2+ chelator) but there was a small but significant increase in the rate of LH release during the second phase response. This increase could be prevented by inhibition of protein synthesis by cycloheximide. Cycloheximide and EGTA did not affect basal release of LH by glands from intact rats, neither did EGTA affect the high basal release of LH by glands from ovariectomized rats. However, the LH-RH-induced release of LH from pituitary glands of ovariectomized rats, which did not show the initial phase of low LH release, was completely suppressed by EGTA throughout a 4-h incubation period. The pattern of LH release stimulated by the combination of N6-monobutyryl cyclic AMP and theophylline (mbcAMP/theophylline) showed an initial phase of low LH release lasting 4 h after which it increased. The magnitude of the effect was small compared with the action of LH-RH. As it did with LH-RH, EGTA completely blocked the initial response, but allowed a small increase in the rate of LH release thereafter; this increase could also be blocked by inhibition of protein synthesis. Addition of EGTA to media during pretreatment of pituitary glands from intact rats with either LH-RH or mbcAMP/theophylline did not impair the facilitatory effect of these secretagogues on the responsiveness of the glands to subsequent exposure to LH-RH and cycloheximide and normal Ca2+ levels. The restoration of Ca2+ levels after withdrawal neither affected basal nor LH-RH-induced release of LH. Exclusion of Ca2+ from the media during a 6-h incubation of pituitary glands from intact rats with LH-RH prevented the glands from becoming refractory to subsequent stimulation by LH-RH, which occurs when normal Ca2+ concentrations are present. The results suggested that extracellular Ca2+ is obligatory for LH release and the induction of refractoriness by LH-RH. In contrast, that part of the action of LH-RH which is cyclic AMP-mediated and protein synthesis-dependent is not affected by withdrawal of extracellular Ca2+.

STUDIES ON A PROTEIN SYNTHESIS DEPENDENT STEP IN LH RELEASE BY LH-RH

1979 ◽  
Vol 92 (4) ◽  
pp. 648-657 ◽  
Author(s):  
J. de Koning ◽  
J. A. M. J. van Dieten ◽  
A. M. I. Tijssen ◽  
G. P. van Rees
Keyword(s):  
Protein Synthesis ◽  
Female Rats ◽  
Protein Factor ◽  
Active Concentration ◽  
Long Time ◽  
Pituitary Glands ◽  
Lh Release ◽  
Lh Rh ◽  
Inhibitor Of Protein Synthesis

ABSTRACT The hypothesis that LH-RH induces LH release partly through a protein synthesis dependent step (protein factor) was further investigated using two different experimental designs. First, during incubation of pituitary glands of intact dioestrous female rats with a maximally active concentration of LH-RH, the inhibitor of protein synthesis cycloheximide was added at various times after the beginning of the incubation. The results show that it takes a relatively long time, i.e. more than 1 h of exposure to LH-RH before the amount of the protein factor has increased sufficiently to allow a maximal LH secretion. Secondly, LH-RH was injected iv after which the protein factor was assayed by incubating the pituitary glands with a maximally active concentration of LH-RH in the presence of cycloheximide and measuring LH release in vitro. It was found that 1 h after the injection sufficient protein factor was present to permit an elevated response to LH-RH. This response could be suppressed by injecting cycloheximide prior to LH-RH. When the interval between injection of LH-RH and beginning of the incubation was increased to 2 h, LH release in vitro decreased again. However, ovariectomy immediately before LH-RH injection resulted in maintenance of the elevated response to LH-RH in vitro, indicating a role of the ovaries in this phenomenon.

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